The invention relates to a safety module and a control process for a multifunctional handheld tool, in particular a hammer with chisel function.
In rotary handheld tools sometimes the tools jam in work piece resulting in an undesired rotation of the housing placing undesired rotation on the operator's hand. In order to prevent this effect, a variety of safety modules are utilized to reliably disconnect the power flow between the electrical motor and the tool in response to a rotational sensor signal based on, for example, the angular acceleration. In purely percussive modes of operation such as chiseling, on the other hand, strong movements of the housing such as slipping of the chisel occur and are acceptable. Disconnection of the power flow in such situations is undesired by the operator.
DE 19628945 A1 discloses a rotary handheld tool with an ATC safety module having a double integration of a rotary movement. The disclosure in this document helps those skilled in the art understand an ATC safety module.
DE 4334933 C discloses a rotary handheld tool for a rotating tool with an anti-torque control (ATC) safety module, which in the event of unacceptable rotations of the housing interrupts the drive train such that unacceptable spatial movements are detected by multi-axis acceleration sensors and evaluated by a fuzzy logic, which in acceptable rotations deactivates the ATC safety module. Different modes of operation are not picked up by the safety module.
DE 19942156 A1 discloses a rotary and percussive combination hammer with chiseling function having an ATC safety module with a rotary sensor sensitive to angular acceleration. In this case, the ATC safety module queries the operating modes of the combination hammer using a Hall sensor on the mode selection switch and the ATC safety module shuts down only in the exclusively percussive mode. The ATC safety module is particularly deactivated in the purely percussive chiseling mode and in the impact drilling mode or rotary drilling mode it is active. The actual mode does not follow directly upon setting the mode selection switch because of the switching delay, whereby the ATC safety module detects an incorrect mode in a brief interphase and is inactive in the protected mode in the case of rotary movement. This is a drawback especially when switching over from a still-running rotary mode to an exclusively percussive mode.